I needed a good bench DC (Direct Current) power supply to power my Yaesu FT-1900R 2 Meter FM Transceiver. The FT-1900R is really designed for mobile operation and requires a 12 Volt, 11 Amp power supply if you want to transmit at a full 55 Watts. I only use my FT-1900R in my Radio Shack and do not go mobile with it. Originally I was using one of those automotive Jump Start battery packs to run my FT-1900R, but when running at a full 55 Watts the Jump Start battery quickly lost charge after only a half hour on a rag-chew.
A Permanent Fix
It was time to find something more permanent. I decided that I would need to purchase a DC bench power supply that could produce at least 12Volts, 12 Amps continuous, this would give me a little "wiggle room" of 1 Amp as the specs of my transceiver indicate the max current consumption was 11 amps. I looked at a couple of web sites that specialize in amateur radio equipment and they wanted an arm and a leg for a basic regulated power supply that would meet my specification. I then decided to look on Amazon to see what they had to offer.
Finding an Inexpensive Power Supply
The cheapest regulated power supplies on Amazon are made by a company called Pyramid. I was a little skeptical of their products as I remember in the 1980s when I was a teenager Pyramid was the company that made low cost stereo equipment of dubious quality. But I decided to take a chance as a Pyramid power supply was half the price of more well known electronic manufacturers.
Linear vs Switching Power Supply
My next decision was to decide between a linear regulated Pyramid PS14KX power supply, which uses a heavy transformer to convert the line current down to the proper voltage and amperage, or a regulated switching power supply like the Pyramid PSV300 which uses a much smaller and lighter transformer but high frequency to convert the line current to the proper Voltage and Amperage.
The problem with the regulated switching power supply is that it is prone to generating a lot of RFI (Radio Frequency Interference) that may interfere with radio's operation. I chose the Pyramid PS14KX linear power supply. I was very excited, my new Pyramid PS14KX power supply arrived two days after I placed the order as I am subscribed to Amazon Prime and get two day shipping by default.
Upon opening the package, I was immediately impressed with the construction of the Pyramid PS14KX power supply, the cabinet was well constructed, it had a fair amount of weight and it did't look "cheap".
The first thing I did was power up the supply with no load and measure the output voltage, it was 13.7 Volts. To test the regulation, I then placed a wire-wound resistor across the output terminals to provide a load that would pull about 5 Amps, the output voltage remained at a constant 13.7 Volts. The next test I did was to connect my Yaesu FT-1900R in receive mode for a half hour then I felt the power supply enclosure and measured the output voltage, still a constant 13.7 Volts and the enclosure was barely warm. Finally, I decided to go for broke and decided to partake in a rag-chew at a full 55 Watts with my FT-1900R connected to the Pyramid power supply. After a half hour rag-chew at full 55 Watts the cabinet of the Pyramid power supply was only slightly warm to the touch and the output was still a constant 13.7 Volts.
Pyramid PS14KX Power Supply on Amazon!
PS14KX Power Supply in my Ham Shack
Here is a picture of my Pyramid PS14KX, powering my Yaesu FT-1900R2 Meter FM Transceiver, in my Radio Shack.
Since those initial tests, I have used the Pyramid PS14KX power supply to power my Yaesu FT-1900R transceiver on my weekly hourly rag-chews for several months and have not had any issues with it. I definitely recommend this DC power supply.
Here is another Amateur Radio enthusiast that gives the Pyramid PS14KX a "thumbs up"!
What is Arduino?
An Arduino, in this case the Arduino Uno, is a low cost (under $30) micro-controller based board intended for non-engineers to create do-it-yourself projects. It has fourteen digital I/O (input/output) pins. These pins are set as digital input by default but can be changed to digital output through programming. In addition, the Uno has six analog I/O pins that are also set as input by default but can be set as output via programming.
In input mode, the Arduino Uno can be used to sense many things such as switch closure as a digital input or sensing a certain voltage, possibly using an external temperature or light sensing device for analog input.
In output mode, the Uno can be used to control external components such as relays, motors, LEDs, and LCD Displays as long as all output does not draw more than 40ma total. External buffering can be put in place to control devices requiring higher current draw.
In its current release, the Uno employs an Atmel ATMege328 microcontroller. The Uno is programmed via USB cable connected to a computer running Windows, MacOS or Linux which has the Arduino IDE (Integrated Development Environment) installed. You program the Uno using an Open Source programming language called Processing which is similar to the C or the C++ programing language.
The Arduino IDE software is free to download from https://www.arduino.cc although they do ask for donations.
The Arduino Uno typically requires an external 9 Volt power supply. I recommend getting one that can source up to 1 Amp. The Uno can also be run off of power supplied via the USB cable connected to a computer or even by 9 Volt battery in situations where external devices connected to it have a very low current draw.
What does the Arduino Uno have to do with Ham Radio?
There has always been a spark of creativity in Ham Radio enthusiasts. From the days where you had to "roll-your-own" receiver and transmitter, as no commercial ones were being manufactured, to the modern days where you want to create a new functionality or augment a functionality that already exists. In the past you had to create functionality using discrete components resistors, transistors, capacitors, and maybe vacuum tubes. If you wanted to change functionally you had to modify the circuit, which involved getting out your soldering iron and adding/removing parts, or possibly rewiring a section. The Arduino Uno allows you to make changes to functionality on the fly by modifying the programming. This allows you to rapidly prototype and bring into production a new functionality in a very short time.
In addition, you can use the Arduino Uno to emulate a functionality of much more costly equipment. For example, there are many plans on the Internet for creating an Antenna Analyzer, a very costly instrument out of reach of most Ham Radio enthusiasts, for a fraction of the cost using an Arduino, a LCD display, and a few circuits created on perfboard.
What about Arduino Uno clones?
The hardware design specifications for the Arduino Uno are openly available, allowing replica or clone boards to be produced by anyone. There are many Arduino clone boards on the market of varying quality. I picked one up recently for a little as $10 from Amazon. These clones for the most part work just as good or better than the actual Arduino Uno board. The clones also interact with ArduinoIDE software just like the real McCoy! I always recommend purchasing a genuine Arduino Uno first! Only purchase a clone after you are familiar with how the Arduino Uno works so that you can anticipate a level of performance from a clone.
The other issue with purchasing a clone is that you are not funding the Arduino organization which has developed and provides upgrades to the ArduinoIDE software.
Below is a picture genuine Arduino Uno (Left) that sells for around a $22 next to a picture of a clone made by Lanmu Uno (Right) that retails for around $9. Nearly identical including same printed circuit board footprint.
Arduino Uno clones on Amazon!
How can I learn Arduino Uno basics?
Programming Electronics Academy offers a free Arduino Crash Course on the Uno. The crash course is a series of recorded sessions. I recommend obtaining an Arduino Uno or Uno clone prior to signing up for the free course so that you can follow the steps in each session. I am in no way affiliated with Programming Electronics Academy but have recently taken their Arduino Crash Course and was thoroughly impressed.
How can I learn about more advanced Arduino Uno topics?
The Programming Electronics Academy also offers fee based recorded sessions on more advanced topics, Your most economical choice is to sign up their annual package which is just under $100 at the time this blog was written. They will also from time to time send out links to free sessions about Arduino Uno advanced topics if you subscribe their e-mail list. In addition, there many great books available on advanced topics such as using the Arduino Uno for robotic applications or as a starting point for a Ham Radio project.
Arduino Ham Radio Books on Amazon!
Where did the Arduino name come from?
The developers of Arduino Uno were looking for a name of their new low cost micro-controller board line of products. The Arduino name comes from the name of a bar in Irvea Italy where the founders of the project used to meet. The bar was named after Arduin of Ivrea, an Italian nobleman that lived from 955 to 1015AD.
Do I need an enclosure for my Arduino Uno?
It is best to limit the amount of contact with the actual components on the Arduino Uno board, but, is perfectly safe to handle at the edges or the I/O connectors. There are many enclosures on the market for Arduino Uno, but I find it more fun to build an enclosure out of Lego's! Below is a picture of an Arduino Uno enclosure I created with attached breadboard for experimention. My 9 year old daughter adorned the top of it with what looks like a mad scientist performing some sort of experiment.
Arduino Enclosures on Amazon!
Based on my blog, I am sure you can appreciate the power of the Arduino Uno! In addition you know where to get basic and advanced training on how to use it. I recommend immediately purchasing an Arduino Uno or clone, experiment with it, and see how this little gem might fit into your next electronic project!
Even MacGyver has an off day:
So my friends nicked named me MacGyver because I can rig up just about anything. Well even MacGyver has an off day. This was evident when I reversed the polarity of the 12V power feeding my Azden PCS-3000 2M FM Radio and I saw smoke exiting the back of the radio's enclosure. I immediately removed power from the radio.
MacGyver Videos on Amazon!
I switched polarity checking to make sure it was right this time then applied power to the Azden PCS-3000 with my finger on the power switch. This time the radio powered up with thankfully no smoke!
Where's the sound?
After fiddling with the volume control and squelch control then checking to make sure the slide switch on the back of the radio was set to internal speaker, I discovered that no matter what I did I could not get any sound from the radio. The front display was working correctly, I could change frequencies and I could tell from the signal indicator that it was picking up broadcasts but I could not hear anything from the speaker.
Time to figure out what I "broke" by reversing the direct current polarity, first you must remove the detachable control unit. This is done by loosening the knobs on each side of the radio.
Organization is important!
When disassembling a radio, I carefully place the parts into two bins, one bin for the larger parts and a smaller bin for the screws.
Remove the control unit from the radio:
Pull the control unit strait forward, the control unit attaches electrically to the body of the radio by an edge connector.
Remove the mounting rails
There are two mounting rails, one on each side of the radio. Two counter sunk Philips screws hold them in place. Remove the screws then pull the rails off.
Top cover Removal:
Remove four screws, two on one side and two on the other; just above where the mounting rails were installed. You should now be able to remove the top cover.
Bottom cover removal:
The bottom cover is held in place with four screws, one at each corner of the cover, simply remove the four screws and pull the cover off. The speaker is attached to the bottom cover, you will need to disconnect the speaker from the printer circuit board.
Upon careful examination I found that some sort of component, possibly a polarized capacitor that bridged the 12 volt input power connection, had exploded. I also noted that the diode across that bridged the 12 volt input power connection had become unsoldered. I removed the broken pieces of the capacitor and re-soldered the broken connection to the diode.
Baofeng 2M Handheld Transcievers on Amazon!
I could not find any other charred or broken components with a visual examination. I know that re-soldering the diode that bridged the 12 volt input power connection would not resolve the problem. Next step is to look at the schematic diagram included with the PCS-3000 manual to trace the circuit paths the speaker takes back to the audio amplifier.
First circuit board:
The speaker connects to a small circuit board mounted on the bottom side of the chassis right by the SO239 external antenna connector. It is labeled "PA" in the schematic which I surmise to mean the RF Power Amplifier board. Upon further examination, it looks like the speaker does not connect to any active components on this circuit board but just acts as a pass through to another circuit board. In the picture I drew a red box around the PA circuit board and circled the external speaker connections.
The destination circuit board:
The audio output connection leaves the PA printed circuit board via a red and black wire then connects to an external speaker jack and a slide switch that allows you to choose between an internal or external speaker. Finally it connects to the RX or Receive circuit board via a green and black connection. In the picture I drew a red box around the circuit board and circled the speaker connection.
The audio amplifier circuit:
Upon further examination, the speaker connection terminates at the output pin 9 of a Toshiba TA7222AP 5.8 Watt Power Amplifier integrated circuit, this was a very common part used in the automotive car stereo, CB,and mobile ham radios in the early 1980s. I circled the TA7222AP location on the RX circuit board.
How can I be sure the TA7222AP was the defective part?
I fired up the old Oscilloscope, turned the radio on then connected the ground connection of the Oscilloscope lead to the metal chassis. I then touched pin 4, the audio input pin, of the TA7222AP integrated circuit with the scope probe and noticed an audio signal. So if an audio signal is going into TA7222AP and not coming out there was a good chance that this integrated circuit had been compromised from the reverse polarity input voltage. I also noticed in the schematic that this integrated circuit connected directly to the 12 volt input DC power making it very susceptible to damage from reverse polarity.
First remove power from the radio, and then remove the screws holding the RX printed circuit board in place. Also note that one screw holds the heat sink tab of the TA7222AP to the chassis of the radio.
TA7222AP capacitor placement:
You should be able to turn over the RX circuit board without removing any of the cabling. Make a note of how the small electrolytic capacitor connects to the TA7222AP before starting the de-soldering process. This capacitor is polarity sensitive and needs to be connected in the same manner as it was removed.
First make a note of the TA7222AP integrate circuit orientation so that you put the replacement in the same way as the defective component was removed. Carefully use solder wick to remove the solder from the pins holding the TA7222AP integrated circuit to the circuit board. Once all of the solder is removed from the pins slowly rock the TA7222AP back and forth until it becomes free and you can remove it from the circuit board.
The replacement TA7222AP should have come in a small package with the pins of the integrated circuit stuck in antistatic foam. Sometimes parts suppliers wrap the component in tin foil as a means of preventing static.
Do not touch the pins of the replacement TA7222AP when removing it from the antistatic foam. Carefully seat the replacement TA7222AP in the same orientation as the defective integrated circuit. Solder all integrated circuit connections to the printed circuit board using a high quality rosin core solder for electronics use.
TA7222AP capacitor soldering:
Re-solder the small electrolytic capacitor to the proper pin of the TA7222AP on the circuit board.
ARRL Ham Radio Books on Amazon!
Prepare to test radio:
Re-seat the RX circuit board but do not yet screw it back in place. Connect the speaker wires to the proper terminals on the PA circuit board. Connect the control unit to the front of the body of the radio. Connect 12v power, making sure to double-check the polarity. Connect the microphone to the front and connect a suitable antenna to the external antenna SO239 connector.
Powering up the radio:
Apply power, it you replaced the TA7222AP correctly you should immediately hear the atmospheric hiss from the speaker, if not check the volume control level and make sure the squelch is not set too high. Also check that the speaker output select switch is set to Internal. Verify all aspects of radio operation.
Buttoning up the radio:
Assembly is just in the opposite order of how you took the radio apart. Remove power and the front control unit before the assembly process. First attach the RX printed circuit board to the chassis with the provided screws, make sure you also attach the heat sink of the TA7222AP integrated circuit to the chassis with the required screw. Make sure the speaker is properly connected to the PA circuit board then install the bottom cover with four screws. Install the top cover with four screws then attach the rails to each side of the body of the radio with two countersunk Philips head screws. Finally attach the control unit to the body of the radio. Secure with two clamps that hold the control unit to the main body by turning the knobs until finger tight.
Repairing an Azden PCS-3000 radio after a mishap is not that difficult; it just takes a little time and effort with the added benefit of getting to better know you radio!
Who Writes This Blog?
John is an IT professional from Cleveland, OH who enjoys amateur radio, ham radio, metal detecting,
Copyright © 2017
Radio Boat Anchor
This page and all the pages on Radio Boat Anchor generate income based on an affiliate relationship with our partners including Zazzle, Amazon, and Google. Prices listed are subject to change without notice.